Fabrication of Silane and Desulfurization Ash Composite Modified Polyurethane and Its Interfacial Binding Mechanism

Polyurethane/desulfurization ash(PU/DA)composites were synthesized using"one-pot method",with the incorporation of a silane coupling agent(KH550)as a"molecular bridge"to facilitate the integration of DA as hard segments into the PU molecular chain.The effects of DA content(φ)on the mechanical properties,thermal stability,and hydrophobicity of PU,both before and after the addition of KH550,were thoroughly examined.The results of microscopic mechanism analysis confirmed that KH550 chemically modified the surface of DA,facilitating its incorporation into the polyurethane molecular chain,thereby significantly enhancing the compatibility and dispersion of DA within the PU matrix.When the mass fraction of modified DA(MDA)reached 12%,the mechanical properties,thermal stability,and hydrophobicity of the composites were substantially improved,with the tensile strength reaching 14.9 MPa,and the contact angle measuring 100.6°.

Research on physical and chemical properties and soundness of dry desulphurized fly ash used as a construction material

The physical and chemical properties and soundness of Baosteel Power Plant＇ s dry desulphurized fly ash were systematically investigated and compared with those of the similar byproducts produced by some other domestic power plants. The feasibility of these byproducts used as a construction material was also analyzed. The results show that Baosteel＇s dry desulphurized fly ash is a kind of ash with high calcium and high sulfur contents, which has the characteristics of volcanic ash activity. It contains sulfate and sulfite, and is easy to cause sulfate activation. It has higher activity compared with common fly ash. But higher calcium sulfite and free-CaO contents in ash will bring about soundness concerns to users. Therefore, quality tests and volume control will be necessary when fly ash is used as a construction material.

Development of Steel Slag-Based Solidification/Stabilization Materials for High Moisture Content Soil

To solve the problems of high moisture content,high viscosity,and poor engineering mechanical properties of soil,this paper using with steel slag(SS)and desulfurization ash(DS)as initial raw materials,realizing the coop-erative treatment of solid waste and solidification of silt soil.The synergistic utilization of SS and DS can reduce the production cost of curing agent and promote its own consumption.According to blended cement of various SS contents and inspected compressive strength performances,the most suitable raw materials ratio was selected.The best formula for this curing agent is cement:steel slag=3:7 with 5%DS,and its 28-day compressive strength can reach 30 MPa.The experiment shows that the effect of DS and Na_(2)SO_(4) reagent with the same quality on early compressive strength improvement of cement and SS system is not much different.In this study,the mineral composition and microstructure of different gel system blocks were characterized by XRD,SEM and EDX,and a large number of webbed structures were found in the SEM test,which was not seen in previous studies.Besides,unconfined compressive strength(UCS),water resistance,and toxic characteristic leaching procedure(TCLP)were used to evaluate silt solidified soil properties.The results demonstrated that the solidified silt could meet not only the standard of general subgrade;but also has a partial stabilization effect of heavy metal ions.

Resource utilization of flue gas calcium-based desulfurization ash:a comprehensive review

Calcium-based desulfurization ash(CDA)is mainly produced in dry and semi-dry flue gas desulfurization processes.The property of CDA is extremely unstable because its main component,calcium sulfite,makes it difficult to be directly applied to the field of building materials.The modification of desulfurization ash can be realized by high-temperature oxidation and wet oxidation.After modification,CDA can be widely used in building materials.Hydrothermal oxidation has broad development prospects because it can complete the oxidation of CDA and the removal of impurity elements at the same time.CDA can be used to prepare high value-added products of calcium sulfate whiskers and ecological rubber fillers.

Low-temperature oxidation behavior and mechanism of semi-dry desulfurization ash from iron ore sintering flue gas

The low-temperature wet oxidation behavior of semi-dry desulfurization ash from iron ore sintering flue gas in ammonium citrate solution was investigated for efficiently utilizing the low-quality desulfurization ash. The effects of the ammonium citrate concentration, oxidation temperature, solid/liquid ratio, and oxidation time on the wet oxidation behavior of desulfurization ash were studied. Simultaneously, the oxidation mechanism of desulfurization ash was revealed by means of X-ray diffraction, Zeta electric resistance, and X-ray photoelectron spectroscopy (XPS) analysis. Under the optimal conditions with ammonium citrate, the oxidation ratio of CaSO_(3) was up to the maximum value (98.49%), while that of CaSO_(3) was only 8.92% without ammonium citrate. Zeta electric resistance and XPS results indicate that the dissolution process of CaSO_(3) could be significantly promoted by complexation derived from the ammonium citrate hydrolysis. As a result, the oxidation process of CaSO_(3) was transformed from particle oxidation to SO_(3)^(2−) ion oxidation, realizing the rapid transformation of desulfurization ash from CaSO_(3) to CaSO_(4) at low temperature. It provides a reference for the application of semi-dry desulfurization ash and contributes to sustainable management for semi-dry desulfurization ash.

Phytotoxicity and groundwater impacts of leaching from thermal treatment residues in roadways

The use of coal fly ash（CFA）, municipal solid waste incinerator bottom ash（MSWIBA） and flue gas desulfurization residue（FGDR） in road construction has become very common owing to its economical advantages. However, these residues may contain toxic constituents that pose an environmental risk if they leach out and flow through the soil, surface water and groundwater.Therefore, it is necessary to assess the ecotoxicity and groundwater impact of these residues before decisions can be made regarding their utilization for road construction. In this study,the physico-chemical characteristics, leaching and phytotoxicity of these residues were investigated. Specifically, multivariate analyses were used to evaluate the contributions of the leaching constituents of the CFA, MSWIBA and FGDR leachates to the germination index of wheat seeds. B, Ba, Cr, Cu, Fe and Pb were found to be more toxic to the wheat seeds than the other heavy metals. Furthermore, the leached concentrations of the constituents from the CFA, MSWIBA and FGDR were below the regulatory threshold limits of the Chinese identification standard for hazardous wastes. Analyses conducted using a numerical groundwater model（Wisc LEACH） indicated that the predicted field concentrations of metals from the CFA, MSWIBA and FGDR increased with time up to about 30 years at the point of compliance, then decreased with time and distance. Overall, this study demonstrated that the risks resulting from MSWIBA, CFA and FGDR leaching could be assessed before its utilization for road construction, providing crucial information for the adoption of these alternative materials.